Writing a spec for sending a mail via API

I want an E-Mail to be sent using a background process whenever an Invite was generated.

What I currently have is this approach: The Invite model has the method send_mail, which sends an E-Mail using the Mandrill API and gem. It also has the method queue_mail adds InviteMailer with the invite's ID to the queue using Resque.

However… Since I'm having sort of a really hard time writing specs for this, I assume this might not be the best approach to send mails.

What I mainly want and need to test:

  • was the mail added to the queue?
  • is InviteMailer working properly?
  • does the mail contain the correct vital information?

Vital informations are: sent to the correct person, contains a link to a specific site and some specific data/text; also I'm not sure how to get the current host to the link.

I don't think this is a rare thing to do, so I wonder what the best practices are.

My testing environment: rspec, capybara, factory girl. I already added VCR, to cache the API-request.


You can use Mailcatcher to fake your mail server, and check received mail via web API:


  • Catches all mail and stores it for display.
  • Shows HTML, Plain Text and Source version of messages, as applicable.
  • Rewrites HTML enabling display of embedded, inline images/etc and open links in a new window. (currently very basic)
  • Can send HTML for analysis by Fractal.
  • Lists attachments and allows separate downloading of parts.
  • Download original email to view in your native mail client(s).
  • Command line options to override the default SMTP/HTTP IP and port settings.
  • Mail appears instantly if your browser supports WebSockets, otherwise updates every thirty seconds.
  • Growl notifications when you receive a new message.
  • Runs as a daemon run in the background.
  • Sendmail-analogue command, catchmail, makes using mailcatcher from PHP a lot easier.
  • Written super-simply in EventMachine, easy to dig in and change.


  1. gem install mailcatcher
  2. mailcatcher
  3. Go to http://localhost:1080/
  4. Send mail through smtp://localhost:1025


A fairly RESTful URL schema means you can download a list of messages in JSON from /messages, each message's metadata with /messages/:id.json, and then the pertinent parts with /messages/:id.html and /messages/:id.plain for the default HTML and plain text version, /messages/:id/:cid for individual attachments by CID, or the whole message with /messages/:id.source.

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Manually implementing a rounding function in C

c floating-point rounding

I have written a C program (which is part of my project) to round off a float value to the given precision specified by the user. The function is something like this